THE EPIDEMIOLOGY OF SEVERE PSYCHIATRIC DISORDERS: IS IT TIME TO PUT THE
It is known that some infectious agents can cause brain diseases
indistinguishable from schizophrenia and manic-depressive illness.
Epidemiological aspects, including winter-spring birth, urban birth, and
migration as risk factors, are also compatible with an infectious cause.
Pet cats are known to carry many infectious agents that can be transmitted to
humans; two studies have demonstrated that individuals with schizophrenia and
manic-depressive illness as compared to well controls have had greater exposure
to cats in childhood. Toxoplasmosis is especially interesting because it
has been reported to affect personality traits and to occasionally cause
schizophrenia-like symptoms. Toxoplasmosis has also been found to affect
neurotransmitters in animal studies. Furthermore, antipsychotic drugs are
known to “have lethal effects on protozoa.” Most importantly,
increased antibodies to toxoplasmosis have been found in the sera of individuals
with schizophrenia and manic-depressive illness. The critical variables
whether toxoplasmosis causes these illnesses may be the timing of the primary